1. Field of the Invention
This invention relates to an elevator, and more particularly, to a driving device for raising and lowering the cage of the elevator.
2. Description of the Prior Art
In a known elevator, a pulley for driving hoisting cables and a device for driving the pulley are usually installed above the top of an elevator shaft, or passage, as on the roof of a building. The cage of the elevator is suspended from the cables at one end thereof, and a counterweight from the other end thereof. The pulley is driven to raise and lower the cage.
The elevator also provided with a safety device. The safety device usually comprises a pair of vertical rails secured to a pair of opposite sidewalls of the elevator shaft, and a lever type roller bogie disposed between each rail and the cage and connected to the cage. Should any hoisting cable have been broken, the weight of the cage bears upon the lever of the roller bogie and the elevator stops automatically. The rails also serve to guide the cage for swing-free movement.
The known elevator has, however, a number of drawbacks. A large space is required for the installation of the pulley and other devices, e.g. on the roof of the building, and hoisting cables, which are large in length. All of these devices need a large space and are expensive. The safety device is also expensive. The maintenance of any of those devices is also a costly job. The cables, which are repeatedly bent and stretched about the pulley, have a short life due to broken wires.